Kinetics of the •OH-radical initiated reactions of acetic acid and its deuterated isomers

Aslan

Dib

et al. 2015

Environ. Sci. Technol.

Self Cite

Hydroxyketones are key secondary reaction products in the atmospheric oxidation of volatile organic compounds (VOCs). The fate of these oxygenated VOCs is however poorly understood and scarcely taken into account in atmospheric chemistry modeling. In this work, a combined investigation of the photolysis and temperature-dependent OH radical reaction of 4-hydroxy-2-butanone (4H2B) is presented. The objective was to evaluate the importance of the photolysis process relative to OH oxidation in the atmospheric degradation of 4H2B. A photolysis lifetime of about 26 days was estimated with an effective quantum yield of 0.08. For the first time, the occurrence of a Norrish II mechanism was hypothesized following the observation of acetone among photolysis products. The OH reaction rate coefficient follows the Arrhenius trend (280-358 K) and could be modeled through the following expression: k4H2B(T) = (1.26 ± 0.40) × 10(-12) × exp((398 ± 87)/T) in cm(3) molecule(-1) s(-1). An atmospheric lifetime of 2.4 days regarding the OH + 4H2B reaction was evaluated, indicating that OH oxidation is by far the major degradation channel. The present work underlines the need for further studies on the atmospheric fate of oxygenated VOCs.

Section: Methodsmentioning

confidence: 99%

“…More details can also be found in previous publications. 23 −27 Photolysis Study (SAGE). Simulation Chamber Description and Experimental Conditions.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Investigation of the Gas-Phase Photolysis and Temperature-Dependent OH Reaction Kinetics of 4-Hydroxy-2-butanone

Aslan

Dib

et al. 2015

Environ. Sci. Technol.

Self Cite

“…More details on the experimental setup can be found in previous publications (Turpin et al, 2006;Szabo et al, 2009Szabo et al, , 2011. Experiments were carried out in a~300 L FEP Teflon film chamber in an air-conditioned laboratory (296 K) and at 1 atm.…”

Section: Simulation Chamber Description and Experimental Conditionsmentioning

confidence: 99%

Reactivity of 3-hydroxy-3-methyl-2-butanone: Photolysis and OH reaction kinetics

Atmospheric Environment

Laversin

Tomás

et al. 2014

h i g h l i g h t s 3H3M2B photolysis is the major oxidation channel in the atmosphere. Slight positive temperature dependence in the OH þ 3H3M2B reaction kinetics. Need for a better understanding of the atmospheric chemistry of oxygenated VOC. a b s t r a c t Hydroxycarbonyl compounds are important secondary reaction products in the oxidation of Volatile Organic Compounds (VOCs) in the atmosphere. The atmospheric fate of these oxygenated VOCs is however poorly understood, especially the relevance of the photolytic pathway. In this work, a combined investigation of the photolysis and temperature-dependent OH radical reaction of 3-hydroxy-3-methyl-2-butanone (3H3M2B) is presented. A photolysis lifetime of about 4e5 days was estimated with a global quantum yield of 0.10. The OH reaction rate coefficient follows the Arrhenius trend (298e356 K) and could be modelled through the following expression: k 3H3M2B (T) ¼ (5.12 ± 0.07) Â 10 À12 exp(À563 ± 119/ T) in cm 3 molecule À1 s À1 . A 3H3M2B atmospheric lifetime of 15 days towards the OH radical was evaluated. Our results showed that the photolysis pathway is the major degradation channel for 3H3M2B. Photolysis products were identified and quantified in the present work with a carbon balance of around 80% enabling a reaction mechanism to be proposed. The present work underlines the need for further studies on the atmospheric chemistry of oxygenated VOCs.

“…Experiments were carried out in a 300‐L Teflon chamber at room temperature and 1 atm. The experimental apparatus used in this work is similar to that used in previous works , and only the main aspects will be described in the following. The reactor is surrounded with a range of fluorescent tubes emitting in the 330–480 nm region with a maximum near 370 nm.…”

Section: Methodsmentioning

confidence: 99%

Atmospheric Chemistry of α‐Diketones: Kinetics of C₅and C₆Compounds with Cl Atoms and OH Radicals

Int J of Chemical Kinetics

Djehiche

Coddeville

et al. 2016

Carbonyls play an important role in atmospheric chemistry due to their formation in the photooxidation of biogenic and anthropogenic volatile organic compounds and their high atmospheric reactivity. The Cl-initiated kinetics of two α-diketones (2,3-pentanedione (PTD) and 2,3-hexanedione (HEX)) have been determined as well as the OH + HEX rate constant using atmospheric simulation chamber experiments and the relative rate method. Up to three different reference compounds were used to assess robust results. The following rate constants (in cm 3 molecule −1 s −1 ) have been obtained at 298 K: k(Cl + PTD) = (1.6 ± 0.2) × 10 −11 , k(Cl + HEX) = (8.8 ± 0.4) × 10 −11 , and k(OH + HEX) = (3.6 ± 0.7) × 10 −12 with a global uncertainty of 30%. The present determinations of Cl-and OH-reaction rate constants for HEX constitute first measurements. Using the present measurements, a recently improved structure-activity relationship for Cl + ketone reactions has been updated by introducing an F(-COCO-) factor of 8.33 × 10 −4 . Atmospheric lifetime calculations indicate that chlorine-initiated oxidation may be a significant α-diketone sink in the marine-boundary layer or in places where high Cl concentrations may be found. C